During electrical equipment maintenance, a disconnecting switch provides an electrical isolation point with a clearly visible disconnection point to ensure the safety of maintenance personnel.
Disconnecting switches cannot be operated under load: they cannot be operated under rated load or large load, nor can they switch load current or short-circuit current. However, those with arc-extinguishing chambers can be operated under small loads and unloaded lines.
Generally, during power-on operations: close the disconnecting switch first, then close the circuit breaker or load switch; during power-off operations: open the circuit breaker or load switch first, then open the disconnecting switch.
When selecting disconnecting switches, the rated voltage, rated current, dynamic stability current, and thermal stability current must all meet the requirements of the application.
The function of a disconnecting switch is to disconnect circuits without load current, providing a clear disconnection point between the equipment under maintenance and the power supply to ensure the safety of maintenance personnel. Disconnecting switches do not have a dedicated arc-extinguishing device and cannot interrupt load current or short-circuit current; therefore, they can only be operated after the circuit breaker has disconnected the circuit.